Method of and apparatus for heating a rotary roll

ABSTRACT

In a rotary roll for heating articles, such as fibers which are to be worked, an annular space is provided within the roll adjacent its outer periphery. A liquid heat transfer medium is placed in the annular space and the roll is heated so that the heat transfer medium is in the boiling state having a liquid phase and a vapor phase. As the roll is rotated centrifugal forces are developed which maintain the liquid phase of the medium against the outer surface defining the annular space. The structure of the roll defining the outer surface of the annular space can be a continuous smooth surface or an undulating surface providing alternate ridges and depressions for improving the effect of the heat transfer medium. The heat medium provides a uniform temperature distribution over the roll.

United States Patent [72] Inventors Takuma Katsumata lnazawa, Aichi Prefecture; Tetsuo Ochl, Nagoya, Alchi Prefecture,

both of, Japan [21 Appl. No. 857,045

[22] Filed Sept. 1 l, 1969 [45] Patented Aug. 17, 1971 [73] Assignee Mitsubishi Jukogyo Kabushikl Keisha Tokyo, Japan [54] METHOD OF AND APPARATUS FOR HEATING A 2,412,733 12/1946 Hornbostelm, 165/104 2,844,887 Hornbostel 165/ 1 04 2,909,849 10/1959 Hornboste1..... 165/ 104 3,257,939 6/ 1966 McDermott. 219/469 3,412,228 11/1968 Miyagi 219/471 3,412,229 11/1968 Seagrave,.lr. 219/469 7 Primary Examiner-J. V. Truhe Assistant EXamt'ner-L. H. Bender Attorney-McGlew and Toren ABSTRACT: In a rotary roll for heating articles, such as fibers which are to be worked, an annular space is provided within ,the roll adjacent its outer periphery. A liquid heat transfer medium is placed in the annular space and the roll is heated so that the heat transfer medium is in the boiling state having a liquid phase and a vapor phase. As the roll is rotated centrifu- "gal forces, are developed which maintain the liquid phase of the medium against the outer surface defining the annular space. The structure of the roll defining the outer surface of the annular space can be a continuous smooth surface or an undulating surface providing alternate ridges and depressions for improving the effect of the heat transfer medium The heat medium provides a uniform temperature distribution over the roll. a

- PATENIED AUG] new 3.600.550

sum 1 or 4 FIG. I

PRIOR ART INVENTORY n umq 013 u/mrn T573110 Ocfl ATTOR NEYS PATHHJELILAUCI 7 |97| j I 3,500 550 sum 3 or 4 INVENTORS Fr-m OM KHTsv HRT H TET'SUO OCH ATTORNEYS Pmlzmmum 1 Ian SHEET l [1F 4 FIG. 5

F-TV 248 246 INVENTORS FIK UMH K HT 'N FJTF? TE 7'5 uo 0619/ BY hi M41! m ATTORNEYS METHOD or AND APPAnATusi-"on HEATING A ROTARY Rom.

SUMMARY OFTHEINVENTIVON" The present invention is directed to the arrangement ofa heated rotary roll for heating articles, such as fibers to be worked, as they pass overthe outer surface of the, roll and, more particularly, it isv directed to the use of a'liquid heat transfer medium contained in an annular space within the roll for affording a uniform temperature distribution over the sur:

face of the roll.

In the past, heated rotary rolls have been widely used, such I as in thread-stretch-plying machines, in draw-winders. and the like. In such rolls, an induction heating coil is. positioned within the body-of the roll for supplying heat to its outer sur-- face. In such known devices the surface temperature of'the roll is maintained relatively uniform when a uniform thermal loading is applied over its entire surface, howeverradisadzvantage arises if a heavy thermal loading is appliedlocallyat. one location on the surface of the roll whereby the temperature at the'location of the thermal loadingis lowered considerably relative to the. remaining surface of the roll- As-la result of this nonuniform thermal loading, an extremelyun--' balanced temperature distribution occurs in the roll, and-as a consequence, since the shaft supporting the. roll provides a continuous dissipation of heat, the temperature distribution on the roll surface adjacent, the rotary shaft-is.disturbedand the temperature distribution across-the surface of them". becomes=nonuniform.

Accordingly, the principal object oft-he-present invention is to, provide a heated rotaryroll'which' avoids the disadvantages experiencedin the past and is .free fromany nonuniformity inthe surface temperature of therollin spiteof anyuneventhe mal loadings on, the roll, particularlywhere individual: heavy thermal loadingsareapplied. I 1

Therefore, in accordance with thepresentinvention, an annular-space isv provided within the rollgadjacent. its. outer vperiphery and the space is filled with a-liquid heat. transfer medium. Located radially inwardly fror'nthe annulan'space is a. heating member .for. raising. the temperature of theheat:

' transfer medium to its boiling p'oint; Thequantityof the-heat transfer me'diumplaced withinthe annular spaceis sufficient so that the medium is incontact with-the entire inner. surface of the outer periphery of'the rolliwhichdefinestheouter surface of the annular space.

As the rollisrotated, the centrifugalforces generated throw: the heat transfer medium outwardly against.thesurfaceiofthe roll'definingthe outer surface of'the annular space: Since. a

sufficientquantityof theheat transfer-medium is1contained- However, at. the location of the heavy, thermalloadingythev. heat transfermedium which is in-a-boilingconditionwill consurface and heat dissipation takes place through the rotary shaft, but also the temperature differentials developed because of local heavy thermal loadings can be removed rapidly with the result that the temperature on the outer surface of the roll is maintained substantially uniform at all times.

The heated rotary roll described above can obtain the desired results as long as the rotational velocity of the roll is maintained below a certain fixed limit which is ascertainable based on the viscosity of the heat transfer medium within the annular space. However, if the velocity of the roll exceeds the fixed limit, a problem arises in that the uniform temperature distribution alongthe surface of the. roll cannot be maintained. Byway of example, if a heavy thermal loading is applied to a single location on the roll surface as the roll is rotated at relatively high speeds the heat transfer medium will be strongly urged against the-entire outer surface of the annular space due to thecentrifugal' forces generatedv and the roll surface and the heat transfer medium will bestripped of their heat. As a result,

the vapor phase of the heat transfer medium within the annular space will condense on thesurface of the liquid phase adjacent tothe outer surface on which the temperature has been lowered due to the local thermal loading with the result that the. latent heat of condensation is released. However, the thermal conductivity of the liquid phase is much smaller than that of the metal'forming the roll and the latent'heat of condensation cannot be conducted efficiently to the. portion of the roll whose temperature has been reduced due to the thermal resistanceof the liquid phase of the heat transfer medium. Consequently, the surface temperature of the roll cannot be main- .tained at a uniform level. Therefore, another object of the present invention is to provide arotary roll which will overcome the above-mentioned problem and maintain the surface temperature of the roll at a uniform level, even if the rotationalspeed'of the roll'does not reach the above-mentioned fixed-limit. V 7

Accordingly, the surface of the roll defining the outer surface-of the-annular space containing the heat transfer medium i's-provided with an undulating surface composed of alternating ridges anddepressions. In such a construction, when highspeed rotation of the roll takes placethe radially inner portionsof the ridged-surfaces of the outer surface of the annular spacewillproject radially inwardly through the liquid phase of the heat transfer medium and will beexposed to the vapor phase. In thisway; whenthe roll is subjected to a predetermined high rotational velocity, the centrifugal forces developed .drivesthe liquid phase of the heat transfer medium into the depressions, that is, the radially outermost portion of the annular space while the inner or ridged surfaces of the outer surface extend through the-liquid phase and are exposed to 'the vapor phase. As a result, the evaporation of the heat transfer medium takes place at the higher temperature pordenseimmediately andrsupply the. heat of condensation-,tothe- Q roll while along the, remaining surfacesof the. roll. wherepthez higher temperature prevails the boiling phenomenonnwill be promoted further tocontinue theremoval of heat. and,,asza result; the temperature differentialicaused bytheheavyther mal loading will disappear: almost instantaneously. Accordingly,.due to .the-pres.ent'invention not only canuneven ness in the temperature distribution-'onrthjeroll surfacebe thereareillustrated and described preferred embodimentsof tions ofthe rolllbody within the annular space, that is, onthe surfaces.exposedthrough the liquid phase within the recesses andat the same. time the condensation of the heat transfer medium at the; lower temperature portions of the roll takes place' on the surfaceof the ridges. With this arrangement of theouter surfaceof the annular space, extremely. low thermal resistances will be present adjacent the lower temperature portions oftherollwhereby. if a heavy localthermal loading is applied. to :therollsurface. the surface temperatures can be equalized-effectively.

The'vario'usfeaturesof noveltywhich characterize the inventiongare pointed outwith particularity in the claims annexedto-andforming apart of this specification; For a better understandingof the invention, its operating advantages and spvecific'objects attained byits use, reference should be had to the;accompanyingzdrawings and descriptive matter in which theinvention.

BRIEF DESCRIPTION OF THEDRAWINGS compensated-where light thermal loadings occur on'therroll 5" ln-thedrawings;

FIG. 1 is a longitudinal cross-sectional view of a heated rotary roll as known in the prior art; 7

FIG. 2 is a longitudinal cross-sectional view, similar tothat in FIG. 1, of one embodiment of a heated rotary roll in accordance with the present invention; I

FIG. 3 is a longitudinal cross-sectional view of a heated rotary roll, similar to that in FIG. 2, illustrating a second embodiment of the present invention;

FIG. 4 is an end view, partly in m'ent shown in FIG. 3;

FIG. 5 is a partial longitudinal cross-sectional view of a third embodiment of the present invention; and

FIG. 6 is an end view, partly in section, of the embodiment set forth in FIG. 5.

cross section, of the embodi- DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In .FIG. 1 a heated rotary roll is shown, such as has been known in the prior art, and is composed of an induction heating coil or similar heater a mounted in a fixed position within the body of the roll b by means of a supporting member 0, such as an iron core, for heating the outer surface of the roll. The

roll b is mounted for rotation on a shaft d. When a uniform thermal loading is applied to the outer surface of the roll b the surface temperature of the roll is maintained relatively uniform. However, if a heavy thermal loading is applied at a single location on the outer surface the temperature at that location is lowered very considerably and, as a result, the surface temperature of the roll becomes unbalanced. Further, a continuous dissipation of the heat in the roll b takes place through the shaft d which serves as the support member for the roll and this characteristic also contributes to an uneven temperature distribution in the surface of the roll 12.

In FIG. 2, one embodiment of the present invention is illustrated which solves the problem of uneven temperature-distribution in the surface of the roll as has been experienced in the prior art. The roll is formed of an outer hollow cylindrical member 10 which is made of a magnetic material having a good thermal conductivity. Within the hollow member acylindrical jacket 12 is positioned closely inwardly from the inner surface of the hollow member and forming an annular space 14 therebetween. A suitable heat transfer medium, such as DOWTHERM (a trade name of a product of the Dow Chemical Corporation) which is a mixture of 26.5. percent diphenyl and 73.5 percent diphenyl oxide, or a medium principally consisting of diphenyl chloride, alkyl napthalene and the like, is enclosed within the space under a predetermined temperature such that at the desired operating temperature of the roll surface, the heat transfer medium being in the boiling state.

Disposed centrally within the roll cylinder or body 10 is a rotary shaft '16 which extends laterally from a bearing box 18. At the end of the rotary shaft spaced from the bearing box, a hub on the roll cylinder lO-is secured to the shaft 16 by a nut 24 in threaded engagement with a screw portion 22 of the shaft. The roll cylinder 10 is arranged to rotate with the shaft 16. In the space between the radially inner surface of the sleeve 12 and theshaft 16 a heater 26 is provided for heating the outer surface of the roll. The heater is.comprised of a cylindrical iron core 28 extending about the shaft and a coil 30 is mounted around the iron core with a predetermined gap provided between the inner surface of the sleeve 12 and the outer surface of the coil. At the end of the core 28 adjacent the bearing box 18, a flange 32 extends radially outwardly In operation, as the shaft 16 is driven by a suitable driving means, not shown, the roll cylinder 10, the sleeve l2, and the heat transfer medium within the annular space 14 rotate as a unit so that the medium inthe annular space is forced outwardly against the inner surface of the roll cylinder 10 by centrifugal force. The quantity of the heat transfer medium filled into the annular space is sufficient to assure' 'that asubstantially equal thickness of the medium is formed dver the entire inner surface of the roll cylinder. Simultaneously, an alternating magnetic flux is produced through the iron core 28 and the roll cylinder 10 by an alternating current flowing in the coil 30 and this magnetic flux heats the roll cylinder'in a uniform manner. The heating operation is continued until the outer surface temperature of the roll cylinder reaches a preset temperature, at which temperature the heat transfer medium being rotated within the annular space reaches its boiling point with aliquid' phase and a vapor phase being established within the annular space 14.

- With the outer roll surface at the desired temperature and the heat transfer medium in the boiling state, if a heavy thermal loading is applied to the surface of the roll cylinder, particularly when the loading is limited to a local or individual section of the surface, a considerable amount of heat is removed from that individual section while the temperature from the remainder of the surface of the roll cylinder is raised with the result that amomentary condition exists .with a lower temperature portion and a higher temperature portion on the surface of the roll cylinder. However, at the local section where the lower temperature exists the boilingheat transfer medium condenses and releases the heat of condensation to that section while at the remainder of the surface experiencing the higher temperatures, the boiling phenomenon is promoted further to remove heat and reduce the higher temperature of v l l o) 2 2) where I A: a thermal conductivity of the rotary heating roll,

A: a cross section area of the rotary heating roll, [3,: heat generation per unit length of the rotary heating roll,

[3 a heat of evaporation or condensation per unit length of the rotary heating roll,

X: a lengthwise coordinate of an arbitrary point on the rotary heating roll,

l: a total length of the rotary heating roll, 0: a temperature at an arbitrary point on the rotary heating roll, I

9,: an ambient temperature,

0,: a preset temperature,

a a heat dissipation factor due to rotation,

a a heat dissipation factor due to thermal loading. In the above equation, the surface temperature of the rotary heating roll isdetermined by the values of )t and 3 However, since the latter is far larger than the former in value, when a temperature difference is caused on the surface of the roll, only the heat transfer through the medium in the annular space serves to eliminate the difference and equalize the tem perature distribution.

By way of example, the distribution of surface temperatures on the roll b in the prior art, as shown in FIG. 1, and the roll 10 according to the present invention, as shown in FIG. 2, where both have the same diameter of 180 mm. and the same length of 100 mm, it indicated in the following table:

Another embodiment of the invention is shown in FIGS. 3 and-'4 in which similar elements of the roll have the same reference numeral with the addition of the prefix 100. Since the structure of the roll in FIG. 3-is similar to thatillustrated in FIG. 2, a detailed description of its arrangement'is not considered necessary. The roll is-comprisedof a:roll cylinder 110 which-is mounted by means of a hub 120 on the endof a rotary shaft 116 which is mounted within a bearing box 118. In the annular space between the shaft 116 andtheinner surface of the roll 110 a sleeve 112 is provided closely adjacent the inner surface of the roll llfl and forming in combination therewith an annular space 114 within whicha heat transfer medium-is filled. Between the sleeve 1'12 and the shaft 11.6 a heater 126 s is provided comprising a cylindricaliron core l28randa-coil bearingbox 118a flange 132 is provided on the .core 128 and is secured to the bearing box by :means-of bolts 1'26=and insulatingspacer tubes 134.

The difference between'thestructure of the roll in. FIGS. .3 and 4, ascornpared to the roll'illustrated in FIG. 2, isthe-alternating longitudinally extending groove and landconstru'ction on the inner surface of the roll cylinder lil0. Asis shown in FIG. 4, lands 138 alternate with grooves 140 around the inner periphery of the roll cylinder 110. In "FIG..2, the innersurface of the cylinder 10 had a continuously circular construction. In this second embodiment of'the. invention, if asuitable amount of the'heat transfer medium is placed within theannular space 114 and the roll cylinder is mtatedat'a sufficiently high speed while it. is being heated, the surface temperature of the cylinder 1 10 reaches a, predetermined temperature and the heat transfer medium is in a boiling condition. The boiling condition of the heat transfermedium canbe assurediby pressurizing the medium in accordance with the predetermined temperature of the roll surface. Due to the high rotational speed of the cylinder l'l'o the heat.transfermediummithinxthe annular space is urged againstthe inner peripheral-surfaceof the roll cylinder by centrifugal force, and theamount of the heat transfer medium and -the-dimensions ofitheilands il'38and grooves l40.aredetermined'in such amanner that the liquid.

phase of the. heat transfer medium is contained within :the grooves 140 while thesurfaces of theilands 138 areexposedrto the vapor portion ofthe medium.

"it is assumed that a localor'isolatedthermalloading is applied tothe surface of'therollcylinder lil0,itssurface.will momentarily undergo an uneventemperature distribution. However, at the portions ofthe surface of the cylinder wherea higher temperature, exists the liquid phaseof the-mediumcontained'within the grooves 140 will boil-more intenselyandthe heat required for such action will be absorbed from therroll surface to therebylower itstemperature. However, at'the location of the local thermal loading the lower temperature whichexists on the surface will be raised asthevapor contacting the lands 138 within the annular space condenses releasing the latent heat of condensation to the surface of the roll cylinder at that location. As a result, the temperature of the roll cylinder is raised inone location while the remainder of the roll cylinder is cooled by the different actions of the heat transfer medium within the annular space and, in particular, due to the construction of the landsand grooves formed in the interior surface of'the-cylinder. As a consequence, a uniform temperature distribution is maintained even where local heavy thermal loadings are applied to the roll. Where the condensation of the vapor phase of the medium takes place, because it condenses onto the lands 138, a much better thermal conductivity is obtained than through the liquid phase portion of the medium with-the heat transferbeing achieved more quickly so that the temperature distribution is equalized in an effective and efficient manner.

.InFIGS. -5 and6, a third embodiment of the present invention is illustrated in which similar elements of the roll are identified by the same reference numerals, however, with the addition of the prefix 200. In FIG. 5, the roll cylinder 210 is rotatably supported at its opposite ends on a sleeve 244 by :meansof bearings 242. Integrally attached to the sleeve 244 is an ironcore 228 within which a coil 230 is mounted with its radially outer surface spaced from the adjacent inner surface .of thesleeve .212 which combines with the inner surface of the cylinder 210-toprovide an annular space 214.

Around the inner peripheral surface of the cylinder 210, a number of nonmagnetic conductive rings 246 are provided .having-a-uniform length in theaxial direction of the cylinder. As .canbe seen-in FIG. 6, the radially inner surface of the rings 246are-provided with alternating lands 248 and grooves 250.

In view of the above description of the invention, it is believed .that it willbe easy for persons skilled in the art to understand'the manner in which this third embodiment operates. The rotationzof-the rollsupported by the bearings 242 affords the requiredcentrifugal forces for distributing the heated heat transfermedium inthe boiling state with itsliquid phase being contained within the grooves 25.0-and its vapor phase contactingthesur'faces of thealands 248. Therefore, the embodiment in FIGS. 5,-and.6=will operate in the same manner as described for theembodiment disclosed in FIGS. 3 and 4 in achieving the desired uniformtemperature distribution across the surface ofthe rollcylinder.

Additionally, since the rings 246 which line the inner surface of the cylinder 210 are made of a nonmagnetic conductive'material, they serve as secondary conductors in the induction heatingzoperation and thereby considerably improve the electriopower factor in heating the surface of the roll cylinder 210. Moreover, since the rings 246 are manufactured separately from .the cylinder 210 it is possible to produce a .large size assembly ofthe rolland rings at a considerably lower cost than wouldbe possible if a single unit grooved about its interior surface weretobe employed.

What'we claimis:

l. Amethodofheating a rotatingroll structure comprising forming aradially shallow sealed annular spacewithin the roll structure,atthecircumferentialwall of the roll, filling a liquid heat transfer mediuminthe annular space in a sufficient quan- ;tity for=providing,theheattransfer medium in contact with the entire surface-of the roll adjacent to its exterior surface, heatingJ-the roll structure'toa'temperature sufficient to bring the heat'itransfer;mediumzto-a boiling'state and providing a liquid phase vandia vapor phase in-the sealed annular space, rotating theroll-structure for generating centrifugal forces for directing theliquidphase of the heat transfer medium against the interior-surface.of'the roll adjacentits exterior surface with the vaporphasebeing spaced from the interior surface, in the annular. space, by=the liquidphase so that when a thermal loading .isapplied to theexterior surface of the roll structure the arrangementof-the heat transfer medium effects uniform distribution of the temperature of the exterior surface of the roll structure.

.2..A.method, as set'forthin claim 1, including providing alternating' grooves and lands on the roll s urface within the annular space adjacent the exterior surface of the roll structure, and supplying the heat transfer medium within the annular space in such a quantity that in the boiling state the liquid phase of the heat transfer medium can be disposed within the grooves with the vapor phase contacting the lands located between the grooves. I

3. A rotary roll for heating an article, such as a fiber, as it is worked, comprising a centrally disposed support member, a cylindrically'shaped member concentrically disposed about and spaced radially outwardly from said support member and forming the outer surface of the roll, wall means, including said member, forming a sealed annular space spaced closely inwardly from the outer surface of the roll, said member being arranged to rotate about the axis of said support member, the sealed annular space within said member being arranged to contain a liquid heat transfer medium capable of being maintained in the boiling state to provide a liquid phase and a vapor phase and so that the liquid phase is sufficient to cover the entire surface of the member defining the outer surface of the annular space, and heating means disposed between said wall means and said support member and heating the heat transfer medium to the boiling state for heating the outer surface of said member.

4. A rotary roll, as set forth in claim 3, wherein said member comprises an outer cylinder forming the outer surface of the roll, and a cylindrically shaped sleeve disposed concentrically about said support member and spaced closely radially inwardly from the inner surface of said cylinder for cooperating therewith to form the annular space for receiving the heat transfer medium,

5. A rotary roll, as set forth in claim 4, wherein the inner surface of said cylinder forming the outer surface of said annular space has a sinuous surface proyiding alternating grooves and lands extending in the axial direction of said support member. y I

6. A rotary roll, as set forth inclaim 4, including a hub member integrally secured to said cylinder for mounting said cylinder on said support member, said support member comprising a rotary shaft, and means for fixing said hub to said shaft.

7. A rotary roll, as set forth in claim 6, wherein said heating means comprises an iron core concentrically disposed about said shaft and spaced radially inwardly from said sleeve,and a coil mounted about said iron core and spaced radially inwardly from the inner surface of said sleeve for forming a predetermined gap therebetween.

8. A rotary roll, as set forth in claim 4, wherein the interior surface of said cylinder is provided with alternating longitudinally extending lands and grooves with the grooves extending radially outwardly away from said support member, the surfaces of said lands being disposed'in spaced relationship from the radially outer surface of said sleeve.

9'. A rotary roll for heating an article, such as a fiber, as it is worked, comprising a centrally disposed support member, a cylindrically shaped member concentrically disposed about and spaced radially outwardly from said support member and forming the outer surfaceof the roll, said member forming ana liquid phase and a vapor phase and so that the liquid phase is sufficient to cover the entire surface of the member defining the outer surface of the annular space, and heating means disposed between said member and said support member for heating the outer surface of said member and heating the heat transfer medium to the boiling state, wherein said member comprises an outer cylinder forming the outer surface of the roll, a cylindrically shaped sleeve disposed concentrically about said support member and spaced closely radially inwardly from the inner surface of said cylinder for cooperating therewith to form the annular space for receiving the heat transfer medium, a hub member integrally secured to said cylinder for mounting said cylinder on said support member, said support member comprising a rotary shaft, and means for fixing said hub to said shaft, said heating means comprising an iron core concentrically disposed about said shaft and spaced radially inwardly from said sleeve, a coil mounted about said iron core and spaced radially inwardly from the inner surface of said sleeve for forming a predetermined gap therebetween, a bearing box positioned at one end of said shaft for rotatably supporting said shaft, said bearing box beinglaterally spaced from the adjacent surface of said core, a bolt assembly for securing said core to said bearing box, said bolt assembly comprising a plurality of bolts extending between said bearing box and said core, and an insulating sleeve enclosing each said bolt for the extent of the space between said bearing box and said core.

10. A rotary roll for heating an article, such as a fiber, as it is axis of said support member, the annular space within said member being arranged to contain a liquid heat transfer medium capable of being maintained in the boiling state to provide a liquid phase and a vapor phase and so that the liquid phase is sufficient to cover the entire surface of the member defining the outer surface of the annular space, and heating means disposed between said member and said support member for heating the outer surface of said member and heating the heat transfer medium to the boiling state, wherein said member comprises an outer cylinder forming the outer surface of the roll, a cylindrically shaped sleeve disposed concentrically about said support member and spaced closely radially inwardly from the innersurface of said cylinder for cooperating therewith to form the annular space for receiving the heat transfer medium, a plurality of concentric rings of the same outside diameter disposed within said cylinder and the outer surfaces of said rings being in surface contact with the inner surface of said cylinder, said rings being concentrically disposed about said support member, and the inner surfaces of said rings being arranged to provide-alternating axially extending lands and grooves with the grooves extending radially outwardly from said lands in the direction of the outer surface of said cylinder, and the surfaces of said lands being spaced radially outwardly from the outer surfaces of said sleeve.

11. A rotary roll, asset forth in claim 10, wherein said support member comprises a tubular member, bearing means being mounted on said tubular member at axially spaced positions, and said cylinder being mounted on said bearing means for rotating about said tubular member. 

1. A method of heating a rotating roll structure comprising forming a radially shallow sealed annular space within the roll structure at the circumferential wall of the roll, filling a liquid heat transfer medium in the annular space in a sufficient quantity for providing the heat transfer medium in contact with the entire surface of the roll adjacent to its exterior surface, heating the roll structure to a temperature sufficient to bring the heat transfer medium to a boiling state and providing a liquid phase and a vapor phase in the sealed annular space, rotating the roll structure for generating centrifugal forces for directing the liquid phase of the heat transfer medium against the interior surface of the roll adjacent its exterior surface with the vapor phase being spaced from the interior surface, in the annular space, by the liquid phase so that when a thermal loading is applied to the exterior surface of the roll structure the arrangement of the heat transfer medium effects uniform distribution of the temperature of the exterior surface of the roll structure.
 2. A method, as set forth in claim 1, including providing alternating grooves and lands on the roll surface within the annular space adjacent the exterior surface of the roll structure, and supplying the heat transfer medium within the annular space in such a quantity that in the boiling state the liquid phase of the heat transfer medium can be disposed within the grooves with the vapor phase contacting the lands located between the grooves.
 3. A rotary roll for heating an article, such as a fiber, as it is worked, comprising a centrally disposed support member, a cylindrically shaped member concentrically disposed about and spaced radially outwardly from said support member and forming the outer surface of the roll, wall means, including said member, forming a sealed annular space spaced closely inwardly from the outer surface of the roll, said member being arranged to rotate about the axis of said support member, the sealed annular space within said member being arranged to contain a liquid heat transfer medium capable of being maintained in the boiling state to provide a liquid phase and a vapor phase and so that the liquid phase is sufficient to cover the entire surface of the member defining the outer surface of the annular space, and heating means disposed between said wall means and said support member and heating the heat transfer medium to the boiling state for heating the outer surface of said member.
 4. A rotary roll, as set forth in claim 3, wherein said member comprises an outer cylinder forming the outer surface of the roll, and a cylindrically shaped sleeve disposed concentrically about said support member and spaced closely radially inwardly from the inner surface of said cylinder for cooperating therewith to form the annular space for receiving the heat transfer medium.
 5. A rotary roll, as set forth in claim 4, wherein the inner surface of said cylinder forming the outer surface of said annular space has a sinuous surface providing alternating grooves and lands extending in the axial direction of said support member.
 6. A rotary roll, as set forth in claim 4, including a hub member integrally secured to said cylinder for mounting said cylinder on said support member, said support member comprising a rotary shaft, and means for fixing said hub to said shaft.
 7. A rotary roll, as set forth in claim 6, wherein said heating means comprises an iron core concentrically disposed about said shaft and spaced radially inwardly from said sleeve, and a coil mounted about said iron core and spaced radially inwardly from the inner surface of said sleeve for forming a predetermined gap therebetween.
 8. A rotary roll, as set forth in claim 4, wherein the interior surface of said cylinder is provided with alternating longitudinally extending lands and grooves with the grooves extending radially outwardly away from said support Member, the surfaces of said lands being disposed in spaced relationship from the radially outer surface of said sleeve.
 9. A rotary roll for heating an article, such as a fiber, as it is worked, comprising a centrally disposed support member, a cylindrically shaped member concentrically disposed about and spaced radially outwardly from said support member and forming the outer surface of the roll, said member forming an annular space spaced closely inwardly from the outer surface of the roll, said member being arranged to rotate about the axis of said support member, the annular space within said member being arranged to contain a liquid heat transfer medium capable of being maintained in the boiling state to provide a liquid phase and a vapor phase and so that the liquid phase is sufficient to cover the entire surface of the member defining the outer surface of the annular space, and heating means disposed between said member and said support member for heating the outer surface of said member and heating the heat transfer medium to the boiling state, wherein said member comprises an outer cylinder forming the outer surface of the roll, a cylindrically shaped sleeve disposed concentrically about said support member and spaced closely radially inwardly from the inner surface of said cylinder for cooperating therewith to form the annular space for receiving the heat transfer medium, a hub member integrally secured to said cylinder for mounting said cylinder on said support member, said support member comprising a rotary shaft, and means for fixing said hub to said shaft, said heating means comprising an iron core concentrically disposed about said shaft and spaced radially inwardly from said sleeve, a coil mounted about said iron core and spaced radially inwardly from the inner surface of said sleeve for forming a predetermined gap therebetween, a bearing box positioned at one end of said shaft for rotatably supporting said shaft, said bearing box being laterally spaced from the adjacent surface of said core, a bolt assembly for securing said core to said bearing box, said bolt assembly comprising a plurality of bolts extending between said bearing box and said core, and an insulating sleeve enclosing each said bolt for the extent of the space between said bearing box and said core.
 10. A rotary roll for heating an article, such as a fiber, as it is worked, comprising a centrally disposed support member, a cylindrically shaped member concentrically disposed about and spaced radially outwardly from said support member and forming the outer surface of the roll, said member forming an annular space spaced closely inwardly from the outer surface of the roll, said member being arranged to rotate about the axis of said support member, the annular space within said member being arranged to contain a liquid heat transfer medium capable of being maintained in the boiling state to provide a liquid phase and a vapor phase and so that the liquid phase is sufficient to cover the entire surface of the member defining the outer surface of the annular space, and heating means disposed between said member and said support member for heating the outer surface of said member and heating the heat transfer medium to the boiling state, wherein said member comprises an outer cylinder forming the outer surface of the roll, a cylindrically shaped sleeve disposed concentrically about said support member and spaced closely radially inwardly from the inner surface of said cylinder for cooperating therewith to form the annular space for receiving the heat transfer medium, a plurality of concentric rings of the same outside diameter disposed within said cylinder and the outer surfaces of said rings being in surface contact with the inner surface of said cylinder, said rings being concentrically disposed about said support member, and the inner surfaces of said rings being arranged to provide alternating axially extending lands and grooves with the grooves extending radially outwardly from said landS in the direction of the outer surface of said cylinder, and the surfaces of said lands being spaced radially outwardly from the outer surfaces of said sleeve.
 11. A rotary roll, as set forth in claim 10, wherein said support member comprises a tubular member, bearing means being mounted on said tubular member at axially spaced positions, and said cylinder being mounted on said bearing means for rotating about said tubular member. 